1. Field of the Invention
The invention relates to a connection arrangement for two superconductor cables.
2. Discussion of Related Art
The transmission of electricity using high-voltage superconductor cables allows high currents to be transmitted through cables of much smaller section than standard cables made of resistive electrical conductors, while limiting electrical losses for the length of the cable, particularly Joule effect losses since this phenomenon is extremely low in superconductivity.
What is known as a “cold dielectric” superconductor cable is made up of a central superconductor comprising at least one superconductive part, a dielectric layer surrounding said central superconductor, a shield surrounding said dielectric layer and that may be made up in whole or in part of superconductors, and a cryogenic enclosure or “cryostat” surrounding said shield. Said cryostat generally comprises two concentric shells that are thermally insulated from each other, e.g. by a vacuum at a level of 10−5 millibars (mbar). A cryogenic fluid contained inside the internal shell of the cryostat cools the central conductor through the dielectric layer, hence the name “cold dielectric”, until it reaches the temperature at which the conductor is in a state of superconductivity. By way of example, this temperature is of the order of −196° C. for what are known as “high-temperature” superconductors.
With cold dielectric superconductor cables, currents of similar magnitudes are lead to flow both in the central conductor and in the shield, in particular if the shield is made up in whole or in part of superconductors. For high-voltage cables, the magnitude of the current may be high, for example, 2400 amps (A).
This is also the case for what are known as “warm dielectric” superconductors, where the conductor comprises a hollow element, generally a tube, in which a cryogenic fluid circulates.
One solution for connecting together two such superconductor cables is to use an arrangement as described in document FR 2 878 654.
That document describes a connection arrangement for shields of superconductor cables, comprising a superconductive connecting cable between shields, the connecting cable comprising a connecting superconductor and a cryogenic sheath surrounding the connecting superconductor, each of the two ends of the connecting superconductor being joined to one of the shields by means of connections that are electrically and thermally conductive.
However, such an arrangement is particularly complex and costly, since it requires an additional entry and outlet for cryogenic fluid and a specific connecting superconductor.